Testing device



July 10, 1945. A, DQ 2,379,947

TESTING DEVICE Filed Sept. 9, 1942 2 Sheets-Sheet 1 IN V EN TOR.

,4. F BAA/DUB BYMAAFKM Patent ed Jul, 10,1945

Adolph F. Bandur, Berwyn, IlL, aasignor to Western Electric Company,Incorporated,- New York, d

N. Ye, a corporation of New York Application, September 9, 194 2, SerialNo. 457,726

4 Claims. 115-183) This invention relates to testing devices andparticularly to devices for ,use in detecting defects in the insulationof electrically insulated.

conducting structures.

An object or this invention is the provision of a simple and practicaldevice for use in testing electrically insulated conducting structuresto dete'ct defects in the insulation thereof.

In accordance with one embodiment of the in vention, as applied to thetesting of enamel insulated electrical loading coil cores of the annulartype to detect defects in the insulation thereof, there is provided afixture comprising a core rest equipped with a spring loadedpin-arranged to pierce'the insulation of the core as meansis actuatedto. cla'mp the coreon the rest.

Fig; 2 is a diagrammatic view of portions of the fixture showing anelectric signal circuit connected to the electrodes, the core be n shownp clamped to the rest and also clamped between I Two electrodes havingwet felt facing strips or pads on their inner opposed side faces arearranged adiacent opposite ends of the core. One of the electrodes ismovable and upon the core being clamped between the electrodes. the'wetfelt strips serve as compressible electrodes which the wet feltelectrode strips; 4

' Fig. 3is an enlarged fragmentary vertical section taken on the line3-3 of Fig.1 with the core clamped to the rest. and I V Fig. 4 is a viewsimilar to Fig. 2 showing an alternative testing fixture and 'signalcircuit for use in detecting insulationldefectsin electrically insulatedloading coil cores.

Referring to the drawings in detail and par; ticularlvto Fig. l, a mainsupport It carries,

thereon a core rest II which is formed with an arcuate 'upper face (Fig.3) for receiving and supporting an annular shaped core l2.- Pivotally vmounted in a slot in thecore rest II is a housing l3 carrying a springloaded in ll, the pin be.-

effectively engage the rounded edges of the inner and outerperipheries'0! the-core as well as the flat end faces thereof. The electrodes areconnected in parallel and in series with the spring loaded pin in anelectrical circuit which includes a signal deviceand when the insulationon the core is not capable of withstanding a desired potential or isotherwise defective at either end thereof, a path for the current isprovided through one or the other of the wet felt strips on theelectrodes, the core, and the piercing pin, and the signal device willbe actuated to indicate that the insulation on the core is defective. E

In an alternative fixture, the insulation on the core is not pierced butthe electrodes. are connected in series .in the electrical signalcircuit and in case the insulation is not capable of withstandi'ngadesired potential "or is otherwise-defective at each end of the core, apath for the current is provided through the core andthe wet feltelectrode strips and an indicationwill begiven that the insulation onthe core' is defective. 1

Other objects and advantages r this invention will be apparent froin'thefollowing detailed description. taken in conjunction with-theaccompanying drawings, in which a v Fig. 1 is a vertical sectional viewofa testing fixture embodying the features of the invention theinneropposed faces of 'thee'lecn for use in detecting defects in theinsulation of i loadingcoi'l cores, 2. core 'being shown supported andclamped on a rest between the electrodes ready for the test;

ping the core 12 on the: el insulation on the core ing arranged in clrest to pierce an' en t and to contact the metallic center thereofwhich,

in the presentcoreis composed of compressed permalloy powder. The coreI! is-clampedto the rest II by means of a pad l6 carried bya. lever l1pivoted at "to a post It inte ral withthe core rest l' l thepad havingan arcuate lower face for ensasinsh the periphery of the core I! thecore I 2;.presses the pad it against the core, whereupon the springloaded pin ll pierces the insulation, thereof. n latch 20 is providedfor holding the lever l'l in its operative position. The pin it isconnected to an electrical signal circuit (Fig. 2)., which wiil'bereferred to hereinafter.

airranged upon the support N at each side of the core rest "are blocks23 and 24 of insulating material, to 'theinner opposed faces of whichare attached electrodes 25 and 26, respectively.

trodes "and l! are compressible -fe1t strips or pads 21, which extenddown into water containers ll carried: on a framework ll attached to thelowerfaee of the support It, the felt strips being maintained constantlywet by capillary action, 1. The block 23 is fixed to the support," andthe block it is secured 'to'an' L-shaped plate cree rier II, which'isslida'ble on the ,upperface of the support ll for movement to and fromthe block "so that'ppposite ends of the core may clamped between the wetfelt strips I'I on the electrode; I! and it, A. spring ll having'opposite' ends attached to the carrier 32, and'the rt ll,-normally"actsto:hold the carrier w p electrode stand-its Bit 3 coretherebetween, a rotatable cam 36 is provided which, is fixed to a shafttl Journalied on spaced standards 38 fixed to the support it. By

swinging a. handle d9 fixed to the cam 84 in a counter-clockwisedirection (Fig. 1) a rise M3 on the cam bears against a vertical arm ofthe L-shaped carrier 32 and. slides it to theleft. as viewed in Fig. 1,thus clamping the core It between the wet felt strips 27 on theelectrodes 25 and 26. It is to be understood that the spring loaded pinM in the housing iii, the lever Ill and the latch 2!? are so mounted andarranged that they are free to move slightly in a lateral direction whenthe cam 3t is actuated to clamp the core l2 between the electrodes.

To the rear end of the shaft 37 (Fig. 1) is attached a crank arm M; tothe outer end of which is pivoted one end of a link 66. The opposite endof the link 66 is pivoted to a guard dd slidsbly mounted on the upperface of the support it. The guard 55 is so shaped and the movementthereof through the crank arm ll and link M is such that when the core62in clamped between the wet felt strips 2'! on the electrodes 255 and2B, the guard 66 cover the core, felt strip and electrodes. The guard ddcarries an arm at (Fig. 1) arranged to engage and move an arm 4W havingone end extending upwardly through a slot in or at both'ends and, ineither case, the ringer will the support it, the lower end of the armtil being operatively connected to a safety switch included in theelectrical circuit (Fig. 2) to be described hereinafter. In timedrelation with the movement of the guard Qt into and out of operativeposition over the core 12 and electrodes 25 and ZSfthe safety switch isclosed and opened.

The above-described fixture is used with an I electrical test set andsignal circuit shown dia-. grammatically in Fig. 2, which comprim asource of electrical energy it, a rheostat M, a voltmeter 52, atransformer 5d," a signal device in the form of a bellringer 58 andasafety switch 55, all suitably connected in the circuit and includingcondubtors 5B and 51 connecting opposite sides of the circuit to theelectrode 25 and spring loaded insulation piercing pinit, respectively,and a conductor be which connects the electrodes 25 and in parallel. v

In sing the fixture and its associated circuit, the rheostat is adjustedto provide the desired potential between the electrodes 25 and 26carrying the wet felt strips 21, which-are connected in parallel and inseries with the pin H. The particular adjustment of the rheostat, it isto be understood, will depend on the type and thickness of thei'nsulationon the core l2, which is to be subjected to the test.

Thecore i2 is then placed on the rest I l and clamped theretoby means ofthe pad ll 021113118 pivoted lever I1 and secured by the latch 20, inthe manner previously described. In this core clamping. operation, thespring loaded pin l6 pierces the insulation of. the core and contactsthe compressed permalloy center thereof. .Thereafter, the slidableelectrode 28 and its wet felt strip 21' is moved towards its companionelectrode 25 and wet felt strip 21 by rotating the cam 34 in a.counter-clockwise direction by means'of the attached handle 39, theoperator holding the. handle in its operative position until'the test iscompleted. In timed relation with the clamping of the core I! between.the wet felt electrode strip 21, the suard 4B is assess? r a moved mmposition thereover and the safety switch is closed, all described.

As clearly shownv in Figs. 2 and 3, the compresslble wet felt electrodestrips 21, when the core I2 is clamped therebetween, engage and shapethemselves tothe rounded inner and outer continuous peripheral edges ofthe core, as well as against the flat annular end faces thereof. Thus,the greater portion of the insulated surface area of the core i2 andparticularly the rounded peripheral edge surface thereof, which may havedefective insulation due to the enamel insulation being too thin aroundthese edges or of breaks therein, areeifectively engaged. In case thecore insulation, which is engaged by the wet felt electrode strips. isbroken or its thickness is such that it afiords a conducting paththrough the permalloy center df the core, the circult is completed andthe bell ringer 54 will be actuated'to indicate the same. The defect inthe insulation may be at only one end of the core in the mannerpreviously indicate the defect. When the circuit is not com pleted withthe core I? clamped between the wet felt electrode strips 27, theinsulation on the core engaged by the electrode strips is consideredacceptable. To complete the insulation test on the inner and outerperipheral surfaces of the core 62 not engaged by the wet felt electrodestrips 21, they are checked visually and also by means of a manuallymoved searching pin passed over these surfaces, the pin being connectedto an electrical signal circuit.

In the alternative embodiment of this invention, shown in Fig. 4, theelectrodes 2dand26 are connected in series by conductors ill and 6| toan electrical signal circuit similar to that used in the hereinbeforedescribed embodiment (Fig.

go 2), wherein, that is, in the latter embodiment,

the insulation piercing pin I4 is connected inseries with the electrodes25 and 26, the letter being connected in parallel. In the-arrangement ofFig. 4, the core I 2 is merely placed on a rest Maud clamped between thewetfelt electrode strips 21 in the manner previously described (Fig. 2)!In case the insulation on the core I! at each end thereof is either toothin, broken, or

" otherwise defective or a combination of such den will be understoodthat the embodiments herein described are merely illustrative of theinvention and one application thereof and that modifications can be madeand it is capable of other applications.

What is claimed is: 1. In a device for detecting defective insulation ofelectrically insulatedconducting structures,

a support for an insulated conducting structure, means for piercingtheinsulation of said structure; relatively movable electrodes having wetcompressible liquid absorbent members for engaging surfaces of thestructure, means for relatively moving said electrodes to clamp thestructure therebetween, and an electric signal circuit connected to saidinsulation piercing means and to said electrodes adapted to be operatedwhen I a current path is provided through said structure due todefective insulation.

2. In a device for detecting defective insulation aerate? ofelectrically insulated conducting structures, a support for an insulatedconducting structure, means for securing the structure to said support,

means eflective simultaneously with the securing of the structure forpiercing the insulation thereof, relatively movable electrodes havingwet compressible liquid absorbent members for engaging tures, a supportfor an insulated conducting structure, means for clamping the structureto said support, yieldable means effective simultaneously with theclamping of the structure for piercing the insulation thereof,electrodes having wet compressible liquid absorbent members for engagingsurfaces of the structure, means for supplying a conducting fluid tosaid members, one of said electrodes being mounted for movement towardsaid otherelectrode, means for actuating said movable electrode to clampthe structure between said electrodes, and an electricsignal circuitconnected to said insulation piercing means and to said electrodesadapted tobe operated when a current path is provided through saidstructure due to defective insulation.

4. In a device for detecting defective insulation of electricallyinsulated conducting structures, a support for an insulated conductingstructure, means for clamping the structure to said support, a springloaded insulation piercing pin in said support, means for clamping thestructure to said support to cause said pin to pierce the insulation ofthe structure, electrodes having wet felt strips secured thereto forengaging opposite surfaces of the structure, a container for conductingfluid into which depending ends of said felt strips extend formaintaining the stripswet by capillary action, one of said electrodesbeing mounted for movement toward said other electrode, means foractuating said movable electrode to clamp the structure between saidelectrodes, and an electric signal circuit connected to said insulation,piercing pin, and to said electrodes adapted to be operated when acurrent path is provided through said structure due to defectiveinsulation.

ADOLPH F. BANDUR.

